The intent of J9D4 is to ensure that the building is ready for the installation of EV charging equipment, should this be desired by a future user of the building.

J9D4(1) mandates that, subject to J9D4(2), carparks associated with Class 2, 3, 5, 6, 7b, 8, and 9 buildings must be equipped with electrical distribution boards that are solely dedicated to EV charging. The reason this clause states that the number of required distribution boards is “subject to J9D4(2)” is to indicate that the number of boards relates to the number of car spaces required to be ready for EV charging equipment. For example, as 10% of car spaces attached to a Class 5 building are required to be EV ready, the carpark associated with the building would need to have at least 100 car spaces on a storey before requiring one EV dedicated distribution board. Additionally, they must be clearly labelled to indicate their specific use for EV charging equipment.
Note: For the purposes of J9D4(1), a carpark is associated with another building if the carpark is on the same site as the building and is provided to serve that building. i.e., a carpark is considered associated with a building if it shares the same property location and is specifically intended to provide parking for the occupants or users of that building.

J9D4(2) has more requirements for these distribution boards. First, each board must be connected to a charging control system capable of managing and scheduling the EV charging based on the building's overall power consumption and needs. For carparks associated with a Class 2 building, the circuits must be capable of supporting an EV charger that delivers a minimum of 12 kWh from 11:00 pm to 7:00 am. Similarly, for Class 5 to 9 buildings, the circuits should support an EV charger delivering a minimum of 12 kWh between 9:00 am and 5:00 pm.  The specified hours match the times when EVs are most likely to require charging for each building type. In Class 3 buildings the capacity should be significantly higher, with each circuit supporting an EV charger needing to deliver a minimum of 48 kWh from 11:00 pm to 7:00 am. The higher capacity matches the anticipated needs of drivers who are likely to have travelled longer distances to get to a Class 3 building.

Beyond current requirements, the provision also looks to the future. While there is no requirement to install EV chargers from the outset, the electrical boards are to be designed to facilitate subsequent installation of 7 kW (32 A) type 2 EV chargers. The percentage of carpark spaces that must be capable of supporting these future installations varies depending on the class of the associated building. Additionally, the boards must contain enough room—specifically, a width of at least 36 mm of DIN rail for each outgoing circuit—for future installation of individual sub-circuit electricity metering of the electricity use of EV charging equipment. This space is to be labelled to denote its purpose.

Limitations and special cases

The provision exempts stand-alone Class 7a buildings from these requirements. This is due to the typically lighter electrical loads of these structures, making the addition of EV charging facilities excessive and unwarranted. However, all other carparks that exist in connection with specific buildings or groups of buildings should adhere to these requirements.